The Infrared Diode Laser Spectroscopy of the nu2 + nu5 - nu2 Hot Band of Acetylene
The infrared diode laser spectrum of the nu2 + nu5 - nu2 hot band of acetylene has been observed within the discharge plasma of acetylene diluted in He. The concentration of acetylene in the nu2 state was modulated by applying a few kHz of ac current, and the spectrum of the hot band was recorded selectively by the discharge modulation technique. In total, 46 P, R, and Q-branch lines have been assigned to the nu2 + nu5 - nu2 hot band and molecular constants including the band origin 727.59318(27) cm-1 were derived. The lifetime of acetylene in the nu2 state was measured to be about 1 ms, proving that the nu2 state is metastable. The collisional relaxation rate constant of acetylene in the nu2 state by helium was measured to be k = 8.01 &plusmn; 0.19 x 10(-14) cm3 molec-1 s-1. Copyright 1998 Academic Press. Copyright 1998Academic Press
Civis
S
J. Heyrovsk&yacute Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague 8, Czech Republic
Zelinger
Z
Tanaka
K